rt

#include <bits/stdc++.h>
using namespace std;

int zhan[1000], index = -1;

void push(int x) {
	index++;
	zhan[index] = x;
}

int pop() {
	int vvv = zhan[index];
	index--;
	return vvv;
}

int top() {
	return zhan[index];
}

int size() {
	return index + 1;
}

int main() {
	
	return 0;
}